Imbalance of Gastrointestinal Microbiota in the Pathogenesis of Helicobacter pylori-Associated Diseases

Impact of helicobacter pylori infection status on outcomes among patients with gastric cancer treated with immune checkpoint inhibitors: A systematic review and meta-analysis

BACKGROUND

Helicobacter pylori (H. pylori), a microaerophilic gram-negative bacterium, is one of the most common chronic bacterial infections in humans, affecting about 50 % of the global population. Recently, it has been proposed that H. pylori infection might impact the efficacy of immune checkpoint inhibitors (ICIs), which are used in the treatment of various cancers, including gastric cancer (GC). However, the impact of H. pylori infection on clinical outcomes in patients with GC treated with ICIs is not yet fully elucidated.

OBJECTIVES

Evaluating the impact of H. pylori infection status on overall survival (OS) and progression-free survival (PFS) on GC treated with ICIs.

METHODS

A meticulous literature search was conducted across PubMed, EMBASE, and Web of Science databases, focusing on studies that compared the effect of H. pylori-positive status versus H. pylori-negative status on patients with GC undergoing ICI treatment. The Newcastle-Ottawa Scale was utilized for the risk of bias assessment of individual studies. For binary outcomes, we used hazard ratios (HRs) or odds ratios (OR) with 95 % confidence intervals (CI) to estimate the effect size.

RESULTS

In total, 3 studies were included, involving 928 patients, of which 396 had H. pylori-positive status. Analysis showed that: PFS was prolonged but not statistically significant in H. pylori-negative patients (HR: 1.11; 95 % CI:0.94-1.31; p = 0.17), OS was significantly prolonged in H. pylori-negative patients (HR: 1.25; 95 % CI: 1.05-1.50; p=0.012), and the H. pylori-negative group had a significant clinical response compared with the H. pylori-positive group (OR: 0.40; 95 % CI: 0.28-0.57; p < 0.000001).

CONCLUSION

In this systematic review and meta-analysis, the status of H. pylori provides a perspective to reshape ICI treatment paradigms and advocates for early eradication treatment of this bacterium.

Helicobacter pylori and rheumatoid arthritis: Investigation of relation from traditional Chinese medicine

Rheumatoid arthritis (RA) is an autoimmune condition that predominantly affects synovial joints, manifesting with joint swelling, pain, and stiffness. In advanced stages, unchecked inflammation can inflict damage on bone and cartilage, resulting in disabilities and deformities of the joints. Additionally, systemic and extra-articular complications may arise due to the consequences of uncontrolled inflammation. Helicobacter pylori (H. pylori) is one of the most prevalent chronic bacterial infections in humans. This microorganism is a spiral-shaped, flagellated, microaerophilic gram-negative bacterium. Prolonged exposure leads to the activation of the immune system, with infected gastric mucosa epithelial cells continuously producing cytokines. This production, in turn, triggers the generation of antibodies as well as T Helper 1 and T Helper 2 effector T cells. The persistent antigenic stimulation resulting from H. pylori infection could lead to the progression of autoimmune diseases. Numerous clinical and pharmacological trials have illustrated the efficacy of traditional Chinese medicine against H. pylori. This review aims to delve into the connection between H. pylori and rheumatoid arthritis so as understand the pathogenesis. The concluding section of this review explores the interplay of Chinese medicine and Helicobacter pylori concerning rheumatoid arthritis.

Plasma metabolomics and lipidomics reveal potential novel biomarkers in early gastric cancer: An explorative study

BACKGROUND

Early identification and therapy can significantly improve the outcome for gastric cancer. However, there is still no perfect biomarker available for the detection of early gastric cancer. This study aimed to investigate the alterations in the plasma metabolites of early gastric cancer using metabolomics and lipidomics based on high-performance liquid chromatography-mass spectrometry (HPLC-MS), which detected potential biomarkers that could be used for clinical diagnosis.

METHODS

To investigate the changes in metabolomics and lipidomics, a total of 30 plasma samples were collected, consisting of 15 patients with early gastric cancer and 15 healthy controls. Extensive HPLC-MS-based untargeted metabolomic and lipidomic investigations were conducted. Differential metabolites and metabolic pathways were uncovered through the utilization of statistical analysis and bioinformatics analysis. Candidate biomarker screening was performed using support vector machine-based multivariate receiver operating characteristic analysis.

RESULTS

A disturbance was observed in a combined total of 19 metabolites and 67 lipids of the early gastric cancer patients. The analysis of KEGG pathways showed that the early gastric cancer patients experienced disruptions in the arginine biosynthesis pathway, the pathway for alanine, aspartate, and glutamate metabolism, as well as the pathway for glyoxylate and dicarboxylate metabolism. Plasma metabolomics and lipidomics have identified multiple biomarker panels that can effectively differentiate early gastric cancer patients from healthy controls, exhibiting an area under the curve exceeding 0.9.

CONCLUSION

These metabolites and lipids could potentially serve as biomarkers for the screening of early gastric cancer, thereby optimizing the strategy for the detection of early gastric cancer. The disrupted pathways implicated in early gastric cancer provide new clues for additional understanding of gastric cancer's pathogenesis. Nonetheless, large-scale clinical data are required to prove our findings.

Human gastric microbiota analysis of refractory H. pylori infection

H. pylori infection is gaining increasing attention, but detailed investigations into its impact on gastric microbiota remain limited. We collected gastric mucosa samples from 47 individuals divided into three groups: 1. Group HP: patients with initial positive H. pylori infection (25 cases); 2. Group ck: H. pylori-negative patients (14 cases); 3. Group DiffHP: patients with refractory H. pylori infection (8 cases). The samples were analyzed using 16S rDNA sequencing and functional prediction with PICRUSt. Group HP showed differences in flora distribution and function compared to Group ck, while Group DiffHP overlapped with Group HP. The abundances of Aeromonas piscicola, Shewanella algae, Vibrio plantisponsor, Aeromonas caviae, Serratia marcescens, Vibrio parahaemolyticus, Microbacterium lacticum, and Prevotella nigrescens were significantly reduced in both Group DiffHP and Group HP compared to Group ck. Vibrio shilonii was reduced only in Group DiffHP compared to Group ck, while Clostridium perfringens and Paracoccus marinus were increased only in Group DiffHP. LEfSe analysis revealed that Clostridium perfringens and Paracoccus marinus were enriched, whereas Vibrio shilonii was reduced in Group DiffHP compared to Group ck at the species level. In individuals with refractory H. pylori infection, the gastric microbiota exhibited enrichment in various human diseases, organic systems, and metabolic pathways (amino acid metabolism, carbohydrate metabolism, transcription, replication and repair, cell cycle pathways, and apoptosis). Patients with multiple failed H. pylori eradication exhibited significant changes in the gastric microbiota. An increase in Clostridium perfringens and Paracoccus marinus and a decrease in Vibrio shilonii appears to be characteristic of refractory H. pylori infection.

Influence of Helicobacter pylori infection on risk of rheumatoid arthritis: a nationwide population-based study

The relationship between Helicobacter pylori infection and rheumatoid arthritis has been investigated, but the results remain controversial. This study aims to determine the association between the two diseases via a 17-year retrospective cohort study. Using the National Health Insurance Research Database, a nationwide population based in Taiwan, we identified 97,533 individuals with H. pylori infection and matched controls between 2000 and 2017 using propensity score matching at a 1:1 ratio. The adjusted hazard ratio of rheumatoid arthritis was determined by multiple Cox regression. The incidence rate of rheumatoid arthritis was 1.28 per 10,000 person-months in the H. pylori cohort, with a higher risk compared to the control group. In the < 30 years old subgroup, the risk was highest, especially in women < 30 years old with H. pylori infection. Patients with < 1 year follow-up showed 1.58 times higher susceptibility to rheumatoid arthritis. Individuals with follow-ups of 1-5 years and over 5 years demonstrated 1.43 and 1.44 times higher risks of rheumatoid arthritis, respectively. Our study showed H. pylori infection was associated with the development of rheumatoid arthritis. Clinicians should note higher risk, especially < 30 years old. More research needed to understand underlying mechanism.

Effect of Helicobacter pylori on immunotherapy is gaining more attention

BACKGROUND

Immunotherapy, especially immune checkpoint inhibitors, has been widely used in tumor therapy and have shown ideal clinical efficacy. However, some cancers still do not respond to PD-1/PD-L1 blockade therapy effectively. Helicobacter pylori infection might affect the curative effect of immunotherapy while it is rarely reported. We aimed to visualize the research hotspots and trends of H. pylori and immunotherapy using a bibliometric analysis to help understand the future development of basic and clinical research.

METHODS

The relevant publications on H. pylori and immunotherapy were searched on April 20, 2022, in the Web of Science Core Collection Database (WOSCC). The document types were limited to articles and reviews. The VOSviewer 1.6.16 software was used to assess the co-authorship, co-occurrence, citation of countries, institutions, authors, journals, and hotspot keywords. The research status and trend change of H. pylori and immunotherapy were analyzed by bibliometric analysis.

RESULTS

A total of 95 studies authored by 561 researchers were eventually included in this study. The majority of the retrieved studies were 55 (58%) original research articles. China conducted the greatest number of studies, followed by USA and Italy. The related topics included the following three aspects: the relationship between microorganisms and cancer, the relationship between gastric cancer and immunity, and the relationship between H. pylori and immunotherapy, including purified/cloned components of H. pylori acting as efficient adjuvant to boost tumor responses and H. pylori infection which modulate host immune responses and impact on the efficacy of antitumor immunity initiated by immune checkpoint inhibitors. The timing diagram revealed that the current research hotspots focused on effects of microorganisms on immunotherapy.

CONCLUSION

The effect of H. pylori on cancer immunotherapy is getting more and more attention in these years. It still remains uncertain, and more studies are needed in the future.

Refractory Helicobacter pylori infection and the gastric microbiota

Background

Curing refractory Helicobacter pylori infection is difficult. In addition, there is currently no research on the gastric microbiota of refractory H. pylori infection.

Methods

We designed a clinical retrospective study involving 32 subjects divided into three groups: 1. nAGHp.a, treatment-naïve patients with H. pylori infection; 2. nAGHp.b, H. pylori-negative patients; and 3. EFHp.a, patients with refractory H. pylori infection. Gastric mucosal samples from the biobank of our research center were collected for 16S rRNA sequencing analysis and bacterial functions were predicted via PICRUSt.

Results

There were significant differences between the H. pylori- positive group and the H. pylori-negative group in species diversity, gastric microbiota structure, and bacterial function. The beneficial Lactobacillus in the H. pylori-positive group were significantly enriched compared with those in the refractory H. pylori infection group. The bacterial interaction network diagram suggested that the microbiota interactions in the refractory H. pylori infection group decreased. The gastric microbiota of the refractory H. pylori infection group was enriched in the pathways of metabolism and infectious diseases (energy metabolism, bacterial secretion system, glutathione metabolism, protein folding and associated processing, sulphur metabolism, membrane and intracellular structural molecules, lipopolysaccharide biosynthesis, ubiquinone and other terpenoid-quinone biosynthesis, inorganic ion transport and metabolism, and metabolism of cofactors and vitamins) when compared with the H. pylori-positive group without treatment based on PICRUSt analysis.

Conclusion

Significant alterations occurred in the gastric microbiota when eradication of H. pylori failed multiple times. A history of eradication of multiple H. pylori infections leads to an imbalance in the gastric mucosal microbiota to a certain extent, which was mainly reflected in the inhibition of the growth of beneficial Lactobacillus in the stomach. Patients with refractory H. pylori infection may be at a higher risk of developing gastric cancer than other H. pylori-positive patients.

The interactions between oral-gut axis microbiota and Helicobacter pylori

In the human body, each microbial habitat exhibits a different microbial population pattern, and these distinctive microflorae are highly related to the development of diseases. The microbial interactions from host different niches are becoming crucial regulators to shape the microbiota and their physiological or pathological functions. The oral cavity and gut are the most complex and interdependent microbial habitats. Helicobacter pylori is one of the most important pathogens from digestive tract, especially the stomach, due to its direct relationships with many gastric diseases including gastric cancer. H. pylori infections can destroy the normal gastric environment and make the stomach a livable channel to enhance the microbial interactions between oral cavity and gut, thus reshaping the oral and gut microbiomes. H. pylori can be also detected in the oral and gut, while the interaction between the oral-gut axis microbiota and H. pylori plays a major role in H. pylori’s colonization, infection, and pathogenicity. Both the infection and eradication of H. pylori and its interaction with oral-gut axis microbiota can alter the balance of the microecology of the oral-gut axis, which can affect the occurrence and progress of related diseases. The shift of oral-gut axis microbiota and their interactions with H. pylori maybe potential targets for H. pylori infectious diagnosis and treatment.

The Effects of Helicobacter pylori Infection on Gastric Microbiota in Children With Duodenal Ulcer

Background

Helicobacter pylori (H. pylori) infection is the main cause of chronic gastritis and duodenal ulcer in children. Little is known about the effect of H. pylori on gastric microbiota in children with duodenal ulcer. This study is aimed at the characteristics of gastric microbiota in children with duodenal ulcer on H. pylori infection.

Methods

We studied 23 children diagnosed with duodenal ulcer by gastric endoscopy because of the gastrointestinal symptoms, 15 children were diagnosed with H. pylori infection, while 8 children were without H. pylori infection. Endoscopic mucosal biopsy samples were obtained for DNA extraction. Microbiomes were analyzed by 16S rRNA profiling and microbial functions were predicted using the software Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt).

Results

Bacterial richness and diversity of gastric microbiota in duodenal ulcer with H. pylori-positive were lower than those negative. The gastric microbiota in H. pylori-positive group significantly reduced proportions of six phyla and fifteen genera; only Helicobacter taxa were more abundant in H. pylori-positive group. Co-expression network analysis showed a more complex network of interactions in the H. pylori-positive group than that in the H. pylori-negative group. For the predicted functions, lower abundance in the pathways of carbohydrate metabolism, signal transduction, amino acid metabolism, and lipid metabolism were found in H. pylori-positive group than the H. pylori-negative group. H. pylori colonization reduces a microbial community with genotoxic potential in the gastric mucosa of children with duodenal ulcer.

Conclusions

The presence of H. pylori significantly influences gastric microbiota and results in a lower abundance of multiple taxonomic levels in children with duodenal ulcer. Children with duodenal ulcer exhibit a dysbiotic microbial community with genotoxic potential, which is distinct from that of children with H. pylori infection.

Clinical Trial Registration

[http://www.chictr.org.cn], identifier [ChiCTR1800015190].

Influence of Helicobacter pylori infection on PD-1/PD-L1 blockade therapy needs more attention

BACKGROUND AND OBJECTIVE

The tumor microenvironment and tumor immunity are crucially involved in tumor therapy. Immune checkpoint inhibitors targeting PD-1/PD-L1 signal transduction have been widely used in tumor therapy and have shown ideal clinical efficacy. However, some kinds of cancers still do not respond to PD-1/PD-L1 blockade therapy effectively, including gastric cancer. The related factors should be explored.

METHODS AND RESULTS

This review summarizes the recent progression of understanding the influence of Helicobacter pylori infection on PD-1/PD-L1 blockade therapy. Current pieces of evidence have indicated that H. pylori infection might affect the curative effect of tumor therapy associating with the induced immunomodulation.

CONCLUSION

It is necessary to understand the overall integration of PD-1/PD-L1 blockade therapy, the tumor microenvironment, and H. pylori infection. Much attention on the influence of H. pylori infection on the efficacy of tumor immunotherapy should be paid.

The impacts of probiotics in eradication therapy of Helicobacter pylori

Helicobacter pylori (H. pylori) is a well-known pathogen that infects approximately half of the world's population. It is a pathogenic agent with potential health hazards related to diverse diseases, especially digestive diseases, such as chronic gastritis, peptic ulcer, and gastric carcinoma. In clinical, antibiotics are commonly applied in eradication therapy of H. pylori. However, the increase in antibiotic resistance and side effects has induced the failure of eradication therapy. Recent studies have shown that probiotic supplementation has promising application prospects. It can restore the gastrointestinal microbiota balance and prevent dysbacteriosis caused by antibiotics. Furthermore, it has been reported to have direct or indirect inhibitory effects on H. pylori. Probiotics may have a beneficial effect on H. pylori eradication. However, the strain, dosages, duration times, and safety of probiotic supplementation need further study before clinical applications.

Helicobacter pylori infection is associated with the co-occurrence of bacteria in the oral cavity and the gastric mucosa

BACKGROUND

Pathogens capable of impacting gastrointestinal tract tumor development are located in the oral cavity, but whether these oral bacteria are able to colonize the gastric mucosa in gastric cancer (GC) patients and whether Helicobacter pylori infection can influence this process remains to be established.

METHODS

Microbial 16S rDNA deep sequencing was conducted to characterize bacteria present in paired gastric mucosa and tongue coating samples in 27 patients with superficial gastritis (SG) and 11 GC patients.

RESULTS

While the overall composition of the gastric mucosa and tongue coating microbiomes differed substantially, certain bacteria were present in both of these communities. The co-occurrence of bacteria between the tongue coating and gastric mucosa differed significantly between SG and GC patients. Of the 15 most abundant shared oral bacteria genera (the core shared oral bacteria), which were associated with differences in microbiota composition between these tongue coating and gastric mucosa, three were enriched in the gastric mucosa of GC patients relative to SG patients, whereas, 12 were depleted in GC patient samples. Furthermore, the prevalence and relative abundance of these core shared oral bacteria in the gastric mucosa were also linked to H. pylori infection status, and the core shared oral bacteria were also associated with the overall composition of the gastric mucosal microbiome.

CONCLUSIONS

Helicobacter pylori infections are linked to the co-occurrence of bacteria in the oral microbiome and the gastric mucosal microbiome. Ectopic colonization of oral microbes may be a primary driver of H. pylori-induced gastric microbial dysbiosis in patients with GC.

Gut microbes in gastrointestinal cancers

Gut microbes (GMs), dominated by bacteria, play important roles in many physiological processes. The structures and functions of GMs are closely related to human health, the occurrence and development of diseases and the rapid recovery of the body. Gastrointestinal cancers are the major diseases affecting human health worldwide. With the development of metagenomic technology and the wide application of new generation sequencing technology, a large number of studies suggest that complex GMs are related to the occurrence and development of gastrointestinal cancers. Fecal microbiota transplantation (FMT) and probiotics can treat and prevent the occurrence of gastrointestinal cancers. This article reviews the latest research progress of microbes in gastrointestinal cancers from the perspectives of the correlation, the influence mechanism and the application, so as to provide new directions for the prevention, early diagnosis and treatment of gastrointestinal cancers.

The Effects of Helicobacter pylori Infection on Microbiota Associated With Gastric Mucosa and Immune Factors in Children

Background

Helicobacter pylori infection is the main cause of chronic gastritis in children. Little is known about the effect of Helicobacter pylori on microbiota and immunity. This study was aimed at characterizing stomach microbiota and immune-regulatory properties of children with Helicobacter pylori colonization.

Methods

We studied 122 children who had undergone gastric endoscopy due to gastrointestinal symptoms, 57 were diagnosed with Helicobacter pylori infection. Endoscopic mucosal biopsy samples were obtained for DNA and RNA extraction. Microbiomes were analyzed by 16S rRNA profiling, with the differentially expressed genes analyzed using RNA sequencing. The RNA-sequencing results of selected genes were validated by qRT-PCR.

Results

Bacterial diversity of Helicobacter pylori-positive gastric specimens were lower than those of negative, and both groups were clearly separated according to beta diversity. Helicobacter pylori-positive group significantly reduced proportions of six phyla and eight genera; only Helicobacter taxa were more abundant in Helicobacter pylori-negative group. Gastric tissues RNA sequencing showed increased expression of multiple immune response genes in Helicobacter pylori -infection. Helicobacter pylori -infected children with restructured gastric microbiota had higher levels of FOXP3, IL-10, TGF-β1 and IL-17A expressions, which were consistent with increased CD4⁺T cell and macrophagocyte, compared with non-infected children.

Conclusions

Presence of Helicobacter pylori significantly influences gastric microbiota and results in lower abundance of multiple taxonomic levels in children. Meanwhile, it affects gastric immune environment and promotes the occurrence of gastritis.

Clinical Trial Registration

[http://www.chictr.org.cn], identifier [ChiCTR1800015190].

Molecular Links Between Alzheimer's Disease and Gastrointestinal Microbiota: Emphasis on Helicobacter pylori Infection Involvement

Alzheimer's disease (AD) is a neurodegenerative disease and the main form of dementia, characterized by progressive cognitive decline and detrimental consequences in both personal-family and global level. Within this narrative review, we provide recent molecular aspects of Tau, a microtubule AD-associated protein, as well as amyloid beta, involved in AD pathophysiology. Moreover, we provide additional emerging data from basic research as well as clinical studies indicating an implicating role of gastrointestinal microbiota (GI-M), including Helicobacter pylori infection (Hp-I), in AD pathophysiology. Likewise, we identified through a molecular prism the current evidence of AD pathogenesis as well as its linkage with GI-M and emphasizing the role of Hp-I. All in all, additional large-scale studies are required for the further clarification of AD pathophysiology and its connection with GI-M and Hp-I, so as novel therapies on molecular basis become available.

In vivo acute toxicity and anti-gastric evaluation of a novel dichloro Schiff base: Bax and HSP70 alteration

Chlorine is shown to possess anti-gastric ulcer activity, since it can inactivate Helicobacter pylori, which is regarded as one of the most common risk factors for causing gastric problems. In the current study, the gastroprotective property of a novel dichloro-substituted Schiff base complex, 2, 2'- [-1, 2-cyclohexanediylbis(nitriloethylidyne)] bis(4-chlorophenol) (CNCP), against alcohol-induced gastric lesion in SD rats was assessed. SD rats were divided into four groups, i.e. normal, ulcer control, testing, and reference groups. Ulcer area, gastric wall mucus, and also gastric acidity of the animal stomachs were measured. In addition, antioxidant activity of CNCP was evaluated and its safe dose was identified. Immunohistochemistry staining was also carried to evaluate two important proteins, i.e. Bcl2-associated X protein (Bax) and heat shock protein 70 (HSP70). Moreover, the activities of super oxide dismutase and catalase, as well as the levels of prostaglandin E2 (PGE2) and malondialdehyde (MDA) were also measured. Antioxidant activity of CNCP was approved via the aforementioned experiments. Histological evaluations showed that the compound possesses stomach epithelial defense activity. Additionally, periodic acid-Schiff staining exhibited over-expression of HSP70 and down-expression of Bax protein in the CNCP-treated rats. Moreover, CNCP caused deceased MDA level and elevated PGE2 level, and at the same time increased the activities of the two enzymes.

Helicobacter pylori Infection and Gastric Microbiota

Owing to its strong acid production, the stomach was known to be a bacteria-free organ for many years. On the other hand, the presence of Helicobacter pylori (H. pylori) and other acid-resistant microbiota that are to persist in the stomach challenged this. It is now recognized that the existence of H. pylori and non-H. pylori species have been linked to the improvement of gastric disease; despite this, there is little published data on the interaction of gastric bacterial flora and the resultant effect on gastric health. The stomach has a unique microbiota including five major phyla, such as Firmicutes, Proteobacteria, Actinobacteria, Fusobacteria and Bacteroidetes. These phyla are identified in both H. pylori-infected and uninfected persons. The resident gastric microflora may mediate the role of H. pylori in the gastric diseases. This article aims to review previous studies that examine the impact of H. pylori infection and the effect of resident gastric microbiota on gut health and disease conditions.

HOW TO CITE THIS ARTICLE

Ozbey G, Sproston E, Hanafiah A. Helicobacter pylori Infection and Gastric Microbiota. Euroasian J Hepato-Gastroenterol 2020;10(1):36-41.

A positive Helicobacter pylori test is associated with low spondylarthritis incidence in a Danish historical cohort study

Ankylosing spondylitis (AS) and undifferentiated spondylarthritis (uSpA) are related inflammatory diseases affecting the spine and joints with infections among possible etiological factors. Helicobacter pylori (H. pylori) may affect the development of inflammatory diseases. Thus, we hypothesized that H. pylori infection affects AS and uSpA development. This cohort study was performed in Denmark with 56,000 patients from primary health care centers who were enrolled when a UBT was performed. They were followed for a median time of 8 years. From nationwide administrative registries, we extracted personal, diagnostic, and treatment information. Prevalence at time of UBT was studied on enrollment using logistic regression and incidence in the follow-up time of 8 years after UBT was studied using Cox regression, comparing H. pylori positive and H. pylori negative patients and adjusting for confounding variables. The prevalence of AS at the time of the UBT was higher among H. pylori positive individuals (OR = 2.00, CI 1.17-3.41), but likely to be linked to confounding as trends disappeared when stratifying for country of birth. The incidence of AS after UBT was lower for individuals who were previously H. pylori positive (OR = 0.23, CI 0.06-0.93). A similar phenomenon was observed for uSpA. As a novel finding, after UBT, the previously H. pylori infected individuals had lower risk of developing AS and uSpA compared to non-infected. This finding may be caused by etiological effects of previous H. pylori infection or unknown confounders. This suggests that H. pylori may somehow be positively involved in the pathogenesis of AS and uSpA.

Helicobacter pylori Infection Aggravates Dysbiosis of Gut Microbiome in Children With Gastritis

Introduction:Helicobacter pylori infection consistently leads to chronic and low degree of inflammatory response in gastric mucosa and is closely related with gastrointestinal and extra-gastric diseases. Effects of local microbiome in the stomach have been studied in adults and children with H. pylori infection. It is, however, not known whether the intestinal microbial community differs in children with varying H. pylori infection. The aim of this study is to characterize the altered composition of microbiome induced by H. pylori infection and in gastritis.

Materials and Methods: This study involved 154 individuals, including 50 children affected by H. pylori-induced gastritis, 42 children with H. pylori-negative gastritis, and 62 healthy controls. Gut microbiome composition was analyzed using 16S rRNA gene-based pyrosequencing. Fecal bacterial diversity and composition were then compared.

Results: On the basis of an analysis of similarities and differences, we found that children with H. pylori-induced gastritis exhibited gut bacteria dysbiosis. The ratio of Firmicutes/Bacteroidetes (F:B) at the phylum level had dramatically decreased in H. pylori-positive gastritis group (HPG) and H. pylori-negative gastritis group (HNG), compared with the healthy control group (HCG). At the family and genus levels, relative abundance of Bacteroidaceae and Enterobacteriaceae was prevalent in HPG and HNG, whereas relative abundance of Lachnospiraceae, Bifidobacteriaceae, and Lactobacillaceae was seen in HCG. Prevalence of different taxa of gut microbiome at the class, order, family, and genus levels was also observed among the three groups.

Conclusions: Gastritis can cause changes in composition of fecal microbiome, which is exacerbated by H. pylori infection. These changes in gut microbiome may be related to drug resistance and development of chronic gastrointestinal diseases.

The eradication of Helicobacter pylori restores rather than disturbs the gastrointestinal microbiota in asymptomatic young adults

BACKGROUND

The eradication of Helicobacter pylori (H pylori) has been suggested to reduce the risk of gastric cancer, but its impact on the gut microbiota has attracted public attention. This study aimed to investigate the short-term and long-term effects of bismuth quadruple therapy on both gastric and fecal microbiota.

METHODS

Ten asymptomatic young adults with H pylori-related gastritis were treated with bismuth quadruple therapy for 14 days, and 7 age-matched adults without H pylori infection were enrolled as healthy controls. Both fecal and gastric mucosa samples were collected from H pylori-positive patients at weeks 0, 6, and 26, while fecal samples were collected from healthy controls. The gastric and gut microbiota were analyzed by 16S rRNA gene sequencing.

RESULTS

The structure of the gastric microbiota was significantly changed after the eradication of H pylori with increased alpha diversity over time. The relative abundance of H pylori sharply decreased from more than 70% to nearly 0% after treatment, while some beneficial bacteria, such as Lactobacillus and Bifidobacterium, were increased. The microbial diversity of gut microbiota was higher in H pylori-infected patients than in healthy controls, which tended to decrease after eradication. The potentially beneficial gut bacteria Blautia and Lachnoclostridium were enriched at week 26 compared to week 0, while the pathogenic Alistipes were depleted to a level close to that of the healthy controls.

CONCLUSIONS

Bismuth quadruple therapy for H pylori eradication can restore the diversity of gastric microbiota with enrichment of beneficial bacteria. The composition of gut microbiota after H pylori eradication trends toward healthy status instead of becoming dysbiotic.

The Contribution of Drugs and Helicobacter pylori to Gastric Mucosa Changes in Patients with Systemic Lupus Erythematosus and Antiphospholipid Syndrome

BACKGROUND

The nature and rate of gastric mucosal (GM) damage in systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) remain to be among the unsolved problems.

OBJECTIVE

To define the role of H. pylori and drugs in the development of GM damages in SLE and APS.

METHODS

A study was conducted on 85 patients with SLE and APS. All the patients underwent esophagogastroduodenoscopy with targeted biopsy of the mucosa of the gastric body and antrum. The presence of H. pylori in the gastric biopsy specimens was determined using polymerase chain reaction.

RESULTS

Endoscopic examination revealed that the patients with SLE and APS on admission had the following GM changes: antral gastritis (82.4%), erosions (24.7%), hemorrhages (8.2%), and pangastritis (8.2%). SLE and APS patients showed no direct correlation between the found GM damages and the presence of H. pylori. The use of glucocorticoid, low-dose acetylsalicylic acid, nonsteroidal anti-inflammatory drug, and anticoagulant in SLE and APS patients is accompanied by GM damage.

CONCLUSION

There was no evidence of the role of H. pylori in GM damage in the SLE and APS patients. More frequent detection of H. pylori was observed in anticoagulants or low-dose acetylsalicylic acid users than in glucocorticoids and nonsteroidal anti-inflammatory drugs ones.

Analysis of culturable microbiota present in the stomach of children with gastric symptoms

Despite extensive studies on the gastric microbiota, including Helicobacter pylori and non-H. pylori, the bacterial composition in children remains unknown. In this study, we analyzed the culturable gastric bacteria in stomach biopsies from 346 children aged 1-15 years affected by gastric diseases. H. pylori and non-H. pylori were identified by specific PCR and 16S rDNA sequencing, respectively. Antibiotic susceptibilities of H. pylori and non-H. pylori were tested by the E-test and disk diffusion methods, respectively. Rapid diagnosis was also performed by H. pylori-specific PCR. Twenty-two H. pylori strains were obtained from culture, and 92 biopsies were positive by H. pylori-specific PCR. The positive rate was higher in boys (40.3%) than in girls (23.3%) (P = 0.001). Resistance rates of 22 H. pylori strains were as follows: metronidazole, 86.4%; tetracycline, 22.7%; amoxicillin, 22.7%; levofloxacin, 31.8%; clarithromycin, 36.4%. Ten isolates were multidrug-resistant. Additionally, among 366 non-H. pylori strains, 204 exhibited urease activity. Non-H. pylori resistance rates were as follows: metronidazole, 94.8%; tetracycline, 26.2%; amoxicillin, 42.6%; levofloxacin, 15.3%; clarithromycin, 46.7%. Our results showed that children with gastric disorders harbor stomach bacteria with urease activity or nitrate reductase activity. Further studies will determine the effects of non-H. pylori bacteria in gastric diseases.

High-Fat Diet Induces Dysbiosis of Gastric Microbiota Prior to Gut Microbiota in Association With Metabolic Disorders in Mice

Accumulating evidence suggests that high-fat diet (HFD) induced metabolic disorders are associated with dysbiosis of gut microbiota. However, no study has explored the effect of HFD on the gastric microbiota. This study established the HFD animal model to determine the impact of HFD on the gastric microbiota and its relationship with the alterations of gut microbiota. A total of 40 male C57BL/6 mice were randomly allocated to receive a standard chow diet (CD) or HFD for 12 weeks (12CD group and 12HFD group) and 24 weeks (24CD group and 24HFD group) (n = 10 mice per group). Body weight and length were measured and Lee's index was calculated at different time points. The insulin sensitivity and serum levels of metabolic parameters including blood glucose, insulin and lipid were also evaluated. The gastric mucosa and fecal microbiota of mice were characterized by 16S rRNA gene sequencing. The body weight was much heavier and the Lee's index was higher in 24HFD group than 12HFD. The insulin resistance and serum level of lipid were increased in 24HFD group compared to 12HFD, indicating the aggravation of metabolic disorders as HFD went on. 16S rRNA gene sequencing showed dysbiosis of gastric microbiota with decreased community diversity while no significant alteration in gut microbiota after 12 weeks of HFD. The phyla Firmicutes and Proteobacteria tended to increase whereas Bacteroidetes and Verrucomicrobia decrease in the gastric microbiota of 12HFD mice compared to 12CD. Moreover, a remarkable reduction of bacteria especially Akkermansia muciniphila, which has beneficial effects on host metabolism, was observed firstly in the stomach of 12HFD group and then in the gut of 24HFD group, indicating the earlier alterations of microbiota in stomach than gut after HFD. We also found structural segregation of microbiota in the stomach as well as gut between 12HFD and 24HFD group, which is accompanied by the aggregation of metabolic disorders. These data suggest that HFD affects not only gut microbiota but also gastric microbiota and the disruption of microbial ecosystem in the digestive tract may play a part in the development and progression of metabolic diseases although molecular mechanism requires further investigation.

The active bacterial assemblages of the upper GI tract in individuals with and without Helicobacter infection

OBJECTIVE

Patients infected with Helicobacter pylori develop chronic gastritis with a subgroup progressing to further complications. The role of microbiota from the oral cavity swallowed with saliva and either transiting the stomach or persisting in the gastric mucosa is uncertain. It is also not known whether the bacterial community differs in luminal and mucosal niches. A key question is whether H. pylori influences the bacterial communities of gastroduodenal niches.

DESIGN

Saliva, gastric and duodenal aspirates as well as gastric and duodenal biopsies were collected during oesophagogastroduodenoscopy from 24 patients (m:9, f:15, mean age 52.2±SD 14.5 years). RNA was extracted and the V1-V2 region of the retrotranscribed bacterial 16S rRNA amplified and sequenced on the Illumina MiSeq platform.

RESULTS

Overall, 687 bacterial phylotypes that belonged to 95 genera and 11 phyla were observed. Each individual comprised a unique microbiota composition that was consistent across the different niches. However, the stomach fluid enriched for specific microbiota components. Helicobacter spp were shown to dominate the mucosa-associated community in the stomach, and to significantly influence duodenal and oral communities.

CONCLUSIONS

The detailed analysis of the active global bacterial communities from the five distinct sites of the upper GI tract allowed for the first time the differentiation between host effects and the influence of sampling region on the bacterial community. The influence of Helicobacter spp on the global community structures is striking.

The gastrointestinal microbiota and its role in oncogenesis

Advances in research techniques have made it possible to map the microbial communities in the gastrointestinal (GI) tract, where the majority of bacteria in the human body reside. Disturbances in these communities are referred to as dysbiosis and have been associated with GI cancers. Although dysbiosis is observed in several GI malignancies, the specific role of these changes has not been understood to the extent of Helicobacter pylori (HP) in gastric cancer (GC). This review will address the bacterial communities along the GI tract, from the oral cavity to the anal canal, particularly focusing on bacterial dysbiosis and carcinogenesis. Just as non-HP bacteria in the stomach may interact with HP in gastric carcinogenesis, the same may hold true for other GI tract malignancies, where an interplay between microbes in carcinogenesis seems conceivable, especially in colorectal cancer (CRC). In the last part of this review we will discuss the potential mechanisms of bacterial dysbiosis in GI carcinogenesis.

Gastric microbiome of Indian patients with Helicobacter pylori infection, and their interaction networks

The gastric microbiome is suspected to have a role in the causation of diseases by Helicobacter pylori. Reports on their relative abundance vis-à-vis H. pylori are available from various ethnic and geographic groups, but little is known about their interaction patterns. Endoscopic mucosal biopsy samples from the gastric antrum and corpus of 39 patients with suspected H. pylori infection were collected and microbiomes were analyzed by 16S rDNA profiling. Four groups of samples were identified, which harbored Helicobacter as well as a diverse group of bacteria including Lactobacillus, Halomonas and Prevotella. There was a negative association between the microbiome diversity and Helicobacter abundance. Network analyses showed that Helicobacter had negative interactions with members of the gastric microbiome, while other microbes interacted positively with each other, showing a higher tendency towards intra-cluster co-occurrence/co-operation. Cross-geographic comparisons suggested the presence of region-specific microbial abundance profiles. We report the microbial diversity, abundance variation and interaction patterns of the gastric microbiota of Indian patients with H. pylori infection and present a comparison of the same with the gastric microbial ecology in samples from different geographic regions. Such microbial abundance profiles and microbial interactions can help in understanding the pathophysiology of gastric ailments and can thus help in development of new strategies to curb it.

The hypothesis that Helicobacter pylori predisposes to Alzheimer's disease is biologically plausible

There is epidemiological evidence that H. pylori might predispose to Alzheimer's disease. To understand the cellular processes potentially linking such unrelated events, we incubated the human gastric cells MNK-28 with the H. pylori peptide Hp(2-20). We then monitored the activated genes by global gene expression. The peptide modulated 77 genes, of which 65 are listed in the AlzBase database and include the hallmarks of Alzheimer's disease: APP, APOE, PSEN1, and PSEN2. A large fraction of modulated genes (30 out of 77) belong to the inflammation pathway. Remarkably, the pathways dis-regulated in Alzheimer's and Leasch-Nyhan diseases result dis-regulated also in this study. The unsuspected links between such different diseases - though still awaiting formal validation - suggest new directions for the study of neurological diseases.

The hypothesis that Helicobacter pylori predisposes to Alzheimer’s disease is biologically plausible

There is epidemiological evidence that H. pylori might predispose to Alzheimer’s disease. To understand the cellular processes potentially linking such unrelated events, we incubated the human gastric cells MNK-28 with the H. pylori peptide Hp(2-20). We then monitored the activated genes by global gene expression. The peptide modulated 77 genes, of which 65 are listed in the AlzBase database and include the hallmarks of Alzheimer’s disease: APP, APOE, PSEN1, and PSEN2. A large fraction of modulated genes (30 out of 77) belong to the inflammation pathway. Remarkably, the pathways dis-regulated in Alzheimer’s and Leasch-Nyhan diseases result dis-regulated also in this study. The unsuspected links between such different diseases – though still awaiting formal validation – suggest new directions for the study of neurological diseases.

The hypothesis that Helicobacter pylori predisposes to Alzheimer’s disease is biologically plausible

There is epidemiological evidence that H. pylori might predispose to Alzheimer’s disease. To understand the cellular processes potentially linking such unrelated events, we incubated the human gastric cells MNK-28 with the H. pylori peptide Hp(2-20). We then monitored the activated genes by global gene expression. The peptide modulated 77 genes, of which 65 are listed in the AlzBase database and include the hallmarks of Alzheimer’s disease: APP, APOE, PSEN1, and PSEN2. A large fraction of modulated genes (30 out of 77) belong to the inflammation pathway. Remarkably, the pathways dis-regulated in Alzheimer’s and Leasch-Nyhan diseases result dis-regulated also in this study. The unsuspected links between such different diseases – though still awaiting formal validation – suggest new directions for the study of neurological diseases.

The Human Stomach in Health and Disease: Infection Strategies by Helicobacter pylori

Helicobacter pylori is a bacterial pathogen which commonly colonizes the human gastric mucosa from early childhood and persists throughout life. In the vast majority of cases, the infection is asymptomatic. H. pylori is the leading cause of peptic ulcer disease and gastric cancer, however, and these outcomes occur in 10-15% of those infected. Gastric adenocarcinoma is the third most common cause of cancer-associated death, and peptic ulcer disease is a significant cause of morbidity. Disease risk is related to the interplay of numerous bacterial host and environmental factors, many of which influence chronic inflammation and damage to the gastric mucosa. This chapter summarizes what is known about health and disease in H. pylori infection, and highlights the need for additional research in this area.

Helicobacter pylori-Induced Changes in Gastric Acid Secretion and Upper Gastrointestinal Disease

Appropriate management of Helicobacter pylori infection of the human stomach is evolving and remains a significant clinical challenge. Acute infection results in hypochlorhydria, whereas chronic infection results in either hypo- or hyperchlorhydria, depending upon the anatomic site of infection. Acute hypochlorhydria facilitates survival of the bacterium and its infection of the stomach. Interestingly, most patients chronically infected with H. pylori manifest a pangastritis with reduced acid secretion due to bacterial virulence factors, inflammatory cytokines, and various degrees of gastric atrophy. While these patients are predisposed to develop gastric adenocarcinoma (~1%), there is increasing evidence from population studies that they are also protected from gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC). Eradication of H. pylori, in these patients, may provoke GERD in predisposed individuals and may be a contributory factor for the rising incidence of refractory GERD, BE, and EAC observed in Westernized societies. Only ~10% of chronically infected patients, mainly the young, manifest an antral predominant gastritis with increased acid secretion due to a decrease in somatostatin and increase in gastrin secretion; these patients are predisposed to develop peptic ulcer disease. H. pylori-induced changes in acid secretion, in particular hypochlorhydria, may allow ingested microorganisms to survive transit through the stomach and colonize the distal intestine and colon. Such perturbation of gut microbiota, i.e. dysbiosis, may influence human health and disease.

Inducible Nitric Oxide Synthase in the Carcinogenesis of Gastrointestinal Cancers

SIGNIFICANCE

Gastrointestinal (GI) cancer taken together constitutes one of the most common cancers worldwide with a broad range of etiological mechanisms. In this review, we have examined the impact of nitric oxide (NO) on the etiology of colon, colorectal, gastric, esophageal, and liver cancers. Recent Advances: Despite differences in etiology, initiation, and progression, chronic inflammation has been shown to be a common element within these cancers showing interactions of numerous pathways. NO generated at the inflammatory site contributes to the initiation and progression of disease. The amount of NO generated, time, and site vary and are an important determinant of the biological effects initiated. Among the nitric oxide synthase enzymes, the inducible isoform has the most diverse range, participating in numerous carcinogenic processes. There is emerging evidence showing that inducible nitric oxide synthase (NOS2) plays a central role in the process of tumor initiation and/or development.

CRITICAL ISSUES

Redox inflammation through NOS2 and cyclooxygenase-2 participates in driving the mechanisms of initiation and progression in GI cancers.

FUTURE DIRECTIONS

Understanding the underlying mechanism involved in NOS2 activation can provide new insights into important prevention and treatment strategies. Antioxid. Redox Signal. 26, 1059-1077.

Non-pylori Helicobacters (NHPHs) Induce Shifts in Gastric Microbiota in Helicobacter pylori-Infected Patients

To explore the effects of gastric non-H. pylori Helicobacter species(NHPH) on the structure and potential function of gastric microbiota, we employed 16S rRNA gene sequencing on 164 gastric biopsy specimens from NHPH (H. suis, H. felis, H. salomonis) /H. pylori coinfection individuals, H. pylori monoinfection individuals and healthy controls. The results demonstrated that marked structural and functional variations between H. pylori mono- and coinfection samples (HPHS, HPHF, HPHM). The changes in bacterial structure induced by NHPH are mainly attributed to their ability of gastric acid secretion inhibition as well as bacterial chemotaxis. Both the HPHS and HPHF groups showed significant increases in phylotype richness and significant decreases in β diversity, but this trend was not found in HPHM group. Regarding the top five phyla and top thirty-five genera, the HPHS and HPHF groups had similar variation trends in relative abundance. The increased relative abundance levels of the genera Vibrio, Pseudoalteromonas, Photobacterium, and Clostridium were associated with increases in predicted signal transduction/metabolic pathways among the three coinfection groups. The relative abundance levels of bacteria involved in the formation of N-nitroso compounds were significantly decreased in the HPHS and HPHF groups (e.g., Streptococcus, Neisseria, Haemophilus, Veillonella, Clostridium, etc.). The significantly decreased relative abundance levels of the phyla Firmicutes and Bacteroidetes in the HPHS and HPHF groups were associated with the observed increases in predicted lipid metabolism pathways. The results in this study implied that NHPH can arouse the variation of structure and function of gastric microbiota, which may pave the way to further research on the pathogenesis of gastric diseases.

Life in the small intestine: the forgotten microbiome?

The gastrointestinal (GI) microbiota is now widely accepted to be an important modulator of our health and well-being. The microbes colonising the GI tract aid in promoting gut and immune homeostasis, while alterations in the composition and/or density of these microbes, often referred to as dysbiosis, have been implicated in many intestinal and extra-intestinal disorders. As a result, the GI microbiota is of increasing interest as a therapeutic target. This is particularly the case in the context of GI disorders linked to chronic inflammation of the mucosa. In this article, we focus on the small intestinal microbiota, which in many senses can be considered the ‘forgotten' gut microbiome.

Helicobacter pylori Infection Aggravates Diet-induced Insulin Resistance in Association With Gut Microbiota of Mice

Emerging evidence suggests that Helicobacter pylori infection is associated with insulin resistance (IR) yet the underlying mechanisms are still obscure. The vital role of gut microbiota in triggering IR has been increasingly reported, however, no study has explored the correlation of gut microbiota and H. pylori-associated IR. Using H. pylori-infected mice model fed different diet structures, we demonstrated that H. pylori infection significantly aggravated high-fat diet (HFD)-induced metabolic disorders at the early stage, the extent of which was close to the effect of long-term HFD. Interestingly, we observed dynamic alterations in gut microbiota that were consistent with the changes in the metabolic phenotype induced by H. pylori and HFD. There may be an interaction among H. pylori, diet and gut microbiota, which dysregulates the host metabolic homeostasis, and treatment of H. pylori may be beneficial to the patients with impaired glucose tolerance in addition to diet control.

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H. pylori infection aggravates high-fat diet induced metabolic disorders at the early stage in C57BL/6 mice.

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H. pylori infection in high-fat diet induces dynamic alterations of gut microbiota consistent with the metabolic phynotype.

H. pylori is one of the most common human bacterial pathogens which causes gastric disorders. Epidemiological studies show that its infection is associated with insulin resistance although the mechanism is obscure. Our study demonstrates that H. pylori infection significantly aggravates high-fat diet induced metabolic disorders at the early stage, accompanied by dramatic alterations of gut microbiota. Moreover, the changes of gut microbiota are consistent with the metabolic phynotype, indicating an interaction among H. pylori, diet and gut microbiota. Thus, the treatment of H. pylori may be beneficial to the patients with impaired glucose tolerance in addition to diet control.

Distinct Clinic-Pathological Features of Early Differentiated-Type Gastric Cancers after Helicobacter pylori Eradication

Background. Gastric cancer is discovered even after successful eradication of H. pylori. We investigated clinic pathological features of early gastric cancers after H. pylori eradication. Methods. 51 early gastric cancers (EGCs) from 44 patients diagnosed after successful H. pylori eradication were included as eradication group. The clinic-pathological features were compared with that of 131 EGCs from 120 patients who did not have a history of H. pylori eradication (control group). Results. Compared with control group, clinic-pathological features of eradication group were characterized as depressed (p < 0.0001), reddish (p = 0.0001), and smaller (p = 0.0095) lesions, which was also confirmed in the comparison of six metachronous lesions diagnosed after initial ESD and subsequent successful H. pylori eradication. Prevalence of both SM2 (submucosal invasion greater than 500 μm) and unexpected SM2 cases tended to be higher in eradication group (p = 0.077, 0.0867, resp.). Prevalence of inconclusive diagnosis of gastric cancer during pretreatment biopsy was also higher in the same group (26.0% versus 1.6%, p < 0.0001). Conclusions. Informative clinic pathological features of EGC after H. pylori eradication are depressed, reddish appearances, which should be treated as a caution because histological diagnosis of cancerous tissue is sometimes difficult by endoscopic biopsy.